Control apparatus



C. C. WHITTAKER.

CONTROL APPARATUS.

APPLICATION FILED DEC.2. 1916.

1,361 ,947. Patefited Dec. 14, 1920.

WITNESSES I INVENTOR I Char/es C W/7I/7d/f6l'.

M BY

ATTORNEY UNITED STATES PATENT OFFICE.

CHARLES C. WHITTAKER, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, -A CORPORATION ,OF PENNSYLVANIA.

common ArPAnA'ros.

1,361,947 Specification of Letters Patent Patented Dec. 14, 1920.

' Application filed December 2, 1916. Serial in. 134,753.

T a-llaghom it may concern. contact segment 2, for a purpose to be de- Be 1t known that 1, CHARLES C. \VHrrscribed. nER, a citizen of the United States, and a A suitable flexible conducting shunt 7 of resldent of \Vilkinsburg, in the county of a well-known type, composed, for example,

Xllegheny and State of Pennsylvania, have of braided copper, is located in parallel relnvented anew and useful Improvement in lation to the spring members 5 and 6, a Control Apparatus, of which the following plurality of rivets 8 serving to suitably elecis a specification. trically and mechanically connect the spring My invention relates to control apparatus members, the conducting shunt and the con- 1 10 and especially to contact fingers-for drum --tact tip; while, for the purpose of permit- 1 controllersand th like, ting connection of the contact finger to an The object of my invention is to provide electrical circuit, a terminal member 9 may a contact finger which shall automatically be secured to the end of the contact finger increase its exerted pressure upon a contact that is remote from the contact tip by means 15 surface in accordance with the increase of Of a Suitable Screw other Circuit-X3011- finger temperature, caused particularly .by necting means, that rig'idly attaches the conweakness of biasing springs and temporarily tact fingerlto a finger-base ll of any suitpoor contactby the finger. able insulating material, in accordance with More specifically stated, it'is the object of a familiar practice. 20 my invention to provide a contact finger Assuming-that the drum controller 1 is embodying a plurality of flat spring memrotated in any suitable manner to effect conbers having materially different temperatact between the segment or segments 2 ture co-eflicients of expansion, the spring thereof and the contact tip or tips 4, my member having the greater co-efficient being present finger acts similarly to contact fin- 25 located remote from the contact surface to gcrs of the prior art in that a suitable conovercome the action of the other spring tact pressure is exerted by the resilient memmember in the direction of increasing the bers 5 and 6, acting in conjunction, while the contact pressure, upon an increase of finger conducting shunt 7 serves tocarry practem )erature. tic-ally all of the current and thus prevent 30 y invention may best be understood by injury'of the spring members by the travreference to the accompanying drawing, ersal therethrough of relatively heavy curwherein Figure 1 is a view, in side elevarents. However, if temporarily poor contion, of a contact finger constructed in actact between the tip 4 and the segment 2' cordance with my present invention and obtains, by reason of weakness of the spring-- 35 also showing the relations of a control drum members or for any other cause, such poor and a stationary supporting means for the contactficauses heating of the t t finger; and Fig. 2 is a plan view of the confaces, as is w n-k d, consequently,

tact finger that is shown in Fig. 1. the temperature of the contact finger is cor- Referring to the drawlng, the structure respondingly increased. 4 0 shown comprises a control drum 1, or the Since the outer spring member 5 has a like, having any suitable number of-contact greater temperature co-efiicient of expansion segments 2 of a familiar type upon which than the inner spring member 6, it-follows a plurality of my control fingers 3 are that the contact finger will be arched in a adapted to bear to complete any desired elec: concave sense with respect to the contact 45 trical circuit, as will beqlndei'stootl. segment 2, or, in other words, the joint The contact finger 3 comprises a tip 4 of action of the two spring members will cause a familiar type, a flat spring member 5 of greater pressure to be exerted between the some material having a relatively great contact tip 4 and the segment 2. Such intemperature co-efiicient of expansion, such creased pressure will effect a reduction of 50 as phosphor bronze or spring brass, and a the finger temperature and, therefore, a balsecond fiat spring member 6 of similar dianced condition will be automatlcally mensions but having a relatively low temreached, wherein the contact pressure is just perature co-efiicient of expansion, such as sufficient to prevent further rise of finger steel the spring member 5 being located on temperature by reason of poor contact.

55 the remote side of the finger from the drum I do not Wish to be restricted to the the direction of increasing sure, upon an increase of ture.

specific structural details, arrangement of parts ormaterials specified in the foregoing description, since various modifications thereof may be made without departing from thespirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

claim as my invention:-

l. A control finger for drum controllers embodying means forautomatically increasing its exerted contact pressure on the drum, upon an increase in the finger temperature.

2. A contact finger for movable controller members embodying means for automatically varying the pressure exerted upon the controller member in accordance with variations of finger temperature.

3. In a controller, the combination with a contact surface, of a contact finger adapted to bear thereupon and embodying means for automatically increasing the contact pressure, upon a temperature increase of the finger by reason of temporarily poor contact.

finger tempera- 6.. In a controller, the combination with a contact surface, of a contact finger adapted to bear thereupon and embodying a contact tip and a plurality of flat spring members secured thereto and having different temperature co-efficients of expansion. 7. In a controller, the combination with a contact surface, of a contact finger adapted 'to bear thereupon and embodying a contact tip and a plurality of flat spring members secured thereto and having different temperature co-efiicients of expansion, the member having the greater co-eificient being located on the side remote from said contact surface.

8. In a controller, the combination with a contact surface, of a contact finger comprising a tip adapted to bear thereupon, a circuit-connecting member, a plurality of flat spring members secured between said tip and said connecting member and having different temperature co-eflicients of expansion, the member having the greater co-eflicient being located on the side remote from said contact surface, and a conducting shunt secured in parallel relation to said spring members.

9. A contact finger for drum controllers embodying individually resilient means having different temperature co-efiicients of expansion for-increasing contact pressure upon the controller surface in accordance with tcn'iperature increases.

10. Acontact finger comprisinga tip, a

plurality of flat spring members secured' thereto and having different temperature coefficients of expansion, and a conducting shunt secured in parallel relation to said spring members.

In testimony whereof I have hereunto subscribed my name this 23rd day of Nov.,

CHARLES C. WHITTAKER. 

